Manufacture of pigmented paper



Patented May 2 6,

i I I I T-ED ,s -T'Es PATENT]oJFF11cE- I '.lmiififfiiififififiifii;

. signorto Merrimac Chemical Company, Everett,

M ass., a corporation Massachusetts No Drawing. Application February 3, 1934, I Serial o.'7o9,593- I 5 Claims. (c1.- 92-21) This invention relates to the manufacture or the usual manner after which the alum is added pigmented paper and it has particular applicato precipitate the size.v Thereafter suflicient sotion to the manufacture of paper wherein zinc dium aluminate is added to produ a p sulphide is employed either alone or in admix-. or more and the zinc sulphide pigment is then 5 ture with clay .or the like. introduced. For the purpose of my in'vention According to present day practice, clay is com- I 175% of um alum ate, based (in-the e ht monly employed as a pigment in the manufacture ofthe pulp, will be found sufiicient and pracof white paper. It serves not only as apig'ment tically no discoloration will be observed. By inbut also as a filling agent. Clay to be used for as ng the fi t of Sod m il u to l this-purpose must of. necessity be of good whit proximately .8'l% no discoloration whatsoever has .10 color and uniform fine texture. These properties been noted. I have added as much as 1.25% or in clay are'not common and accord h ly'the cost Sodium aluminatfi-wheleby a P s Produced the'reofis relatively high. Furthermore, in order with the result that the product appeared to be v r to produce the desired quality of paper, relatively W l Sized and s of excellent Shade? I large amounts of clay arerequired; The functionof the sodium aluminate in pre- 15 It has been proposed heretofore to employ zinc serving and in fact improving the pigment qualsulphide asa substitute forclay. Unlike clay this y of the zinc sulp e s not cl a understood, material is produced chemically of readily availl ou h it app s to b dependent p able constituents and-it'enjoys the further addiliohs which affOTd'gOOl-l Sizing W e avoid vantage in that comparatively small amounts are h i conditions which Obtain when u 2 0 necessary to' produce the desired degree of pi alone is employed as the source 'of alumina; mentatlon. On the other hand, due to its'rea-c- T p f rr d range 'b tw en 5.5 and 7.6. The tivity it sometimes suflers the disadvantage of gh r'limits produce s i factory re ults u discoloration which is very noticeable when ,emsince they neces Substantially greater q ployed under conditions which prevail in the mantitles of Sodium ate t e ultimate product '25 ufacture of paper wherein clay is now utilized. i r expensive. v r. P p p t/ To illustrate: 125 parts of pulp are suspended in of good qua ty m y be O t at lower P the usual manner in water and intimately mixed a e w t n e a me d s with approximately 6.25 parts of commercial zinc h following p fi example st tes one sulphide pigment-whereupon the mixture is sized e bodiment ofmy invention: 30 by adding 2%of sodium resinate, based on the P by weight of p e beaten w th weight of the pulp, and approximately 2% by viater to the usual consistency after which 2.5 weight of alum to precipitate the resinate, after P ts O Sodium resinate. which h p v y which a sheet is formed therefrom. Apparently been dispersed in a is d The Size is p the sheet made under these conditions i inherta ed in e usual manner add 9-1 ently susceptible to discoloration, particularly a ely 2.5 'pa ts' o p p s a u when exposed to metals such as copper andsolu- The resultant-mixture has a 1 Of bout 4-3- tions of acid reacting. electrolytes, though the dis To adju t t DH 0 t mix p p tory for. t e

coloration is not always manifest. A clay filled audition 0f e sulphide p ent, -.66% by wei t 40 paper made under the same conditions remains of Sodium illuminate, based 011 h amount 40 perfectly white. :pu1p, isintroduced whereby a pH of 4:9 is ob-- I have now=found that the discoloration m'ay T o p t of c su p d ar be obviated effectively and, that a, product e added; very little discoloration is evident under ing inordinate durability as well as whiteness is t s n y increasing ,th amount of obtainable provided the compounding of the paper Sodium aluminate to l- 111p havin a pH of 45 is effected under controlled conditions, the deis'produced w ich may be handled under tails of which are hereinafter set forth. the usual p p r nuf t rin c nditions with According to the present i nvention a product perfect safety and no app e discolorationhaving excellent color and durability is obtained It is to be understood h e p se O der by the addition of a small amount of basic aluof adding the. ingredients may be va Thus, 50 I mina, preferably in the form of sodium alumie sulphide. may be added befo e o du g the" nate,whereby the pH value of the pulp is raised addition of the alum, care being exercised to avoid from approximately 4.2 to more than5 and prefcommingling 0f the P t w th an aqueous erably between 5.5 and -7. In practicingmy inmedium'of high i 'eo n good ventionthepulp is mixed with the rosin size in Sizing can be realized with h? aid sodium '5 aluminate and alum at a pH which is more nearly neutral than when alum alone is employed as is described, for example, in United States Patent 1,885,185.

The relative amounts of sodium resinate, alum,

and sodium aluminate may be varied as is well understood by those skilled in the art provided the ultimate pH value of the mix falls within the range hereinabove specified. It is likewise to be noted that" other materials may be incorporated and that the point at which the sodium aluminate and pigment are added by the paper manufacturer is optional, although it is particularly convenient to add the same in the paper beater. Other soaps than sodium resinate may be employed and the nature of the pulp may be modified and'mixed with other fibers as is well understood by those skilled inthis art.

Although I have described one specific example of the application of the principles of my invention and have indicated the effect of variables, it is to be understood that the invention is not restricted to the precise embodiment set forth except as indicated by the appended claims.

What I claim is:

1. A' process of making paper, comprising precipitating rosin size upon paper pulp suspended in water, by adding aluminum sulphate thereto in an amount to obtain precipitation of the rosin and an acidity of the water substantially greater than neutrality, subsequently adding sodium aluminate to obtain substantial neutrality of the water, adding zinc sulphide pigment to the pulp and collecting the pulp as a paper web.

2. A method of manufacturing paper which comprises admixing paper pulp, rosin sizing and Zinc sulphide with water and precipitating the sizing upon the pulp with aluminum sulphate and sodium aluminate, the ratios of the two being so adjusted as to obtain a pH value of approximately 5-7.6 whereby discoloration of the product due to decomposition of the zinc sulphide is obviated.

3. A method of manufacturing paper which comprises admixing paper pulp, sizing and zinc sulphide with water,'a sizing operation being effected by adding sodium aluminate and aluminum sulphate in a ratio to obtain a pH value of the mixture ofapproximately 5-7.6, the zinc sulphide being added to the stock after the sizing has been added and the pH value adjusted within the desired limits, whereby discoloration. of the product due to reaction of zinc sulphide is eliminated.

4. A method of manufacturing paper which comprises admixing paper pulp, sizing and zinc sulphide with water, a sizing operation being effected by adding aluminum sulphate and sodium aluminate in a ratio to obtain a pH value of the mixture of approximately 5-7.6.

5.. In the manufacture of a sized paper contain- 2 ing a zinc sulphide filler or pigment and where aluminum sulphate is employed in the sizing operation, the method of avoiding discoloration and related objectionable manifestations incident to the presence of the zinc sulphide filler,

characterized by the addition of sodium aluminate in sufiicient quantity to bring the pH value within approximately the range of 4.9 to 7.6. 

